Casting

Casting

1. split pattern casting

   • casting involves pouring metal, which has been heated and melted, into a mould
     • any waste material can be re-melted and used again (re-cycled).
       • sand casting is used to shape metals such as cast iron, aluminium and brass.
   • method
     • a pattern is made from timber, e.g. MDF or jelutong. the pattern is made in two halves and attached to a board
       • the pattern is sandwiched between open boxes called cope and drag.
         • a special, oil-bound sand is used to fill each box.one of the boxes also contains two tapered wooden pegs or sprues, which form the pouring spout (runner) and the riser to let the air out.
           • the pattern is removed and the space left is filled with molten metal.

2. lost pattern casting

   • forms metals e.g. aluminium, in complete forms
   • method
     • a pattern is made from polystyrene foam.
       • the foam is buried into the sand and runner and riser added.
         • the molten metal is poured into the mould and instantly burns away the polystyrene foam the space is filled with hot metal that's been poured into the cavity

3. industrial casting

   • method
     • metal is heated in a crucible until molten.
       • a hydraulic ram pushes quantities of the molten metal into the mould.
         • preasure is maintained until the metal has cooled enough for mold to be opened and component taken out.

4. die casting in schools

   • using low melting point point pewter melted with an electric paint stripper gun or blow lamp
     • pouring the pewter into holes easily - worked materials , e.g. cuttlefish, high density modeling foam, MDF or acrylic